LeetCode——627. Swap Salary（数据库,sql）

题目链接

Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values to m and vice versa) with a single update query and no intermediate temp table.

| id | name | sex | salary |
|----|------|-----|--------|
| 1  | A    | m   | 2500   |
| 2  | B    | f   | 1500   |
| 3  | C    | m   | 5500   |
| 4  | D    | f   | 500    |

| id | name | sex | salary |
|----|------|-----|--------|
| 1  | A    | f   | 2500   |
| 2  | B    | m   | 1500   |
| 3  | C    | f   | 5500   |
| 4  | D    | m   | 500    |

题解：

本来想用问号表达式，发现sql中没有，用IF也不会，就参考了下几种解法，不得不说异或确实不错。

UPDATE salary SET sex = IF(sex = 'm', 'f', 'm')

UPDATE salary    SET sex  = (CASE WHEN sex = 'm'   THEN  'f'  ELSE 'm'   END)

UPDATE salary SET sex = IF(sex = 'm', 'f', 'm')